Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong Single-Cycle Optical Fields

We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a field less or on the order of 1 V/Angstrom causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a femtosecond time scale. These phenomena are due a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways.Comment: 4 pages, 4 figure

Predicted Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong Single-Cycle Optical Fields

We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a ≲1  V/Åfield causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a ∼1  fs time scale. These phenomena are due to a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways

Usability assessment of an intraoperative planning software

Usability is a crucial aspect of medical device safety. The brand-new European Regulation requires the manufacturer to assess the usability of the new medical devices. In this study, we evaluate the usability of a new medical device intended to assist the intraoperative planning with the visualization of 3d patient-specific organ models. The usability study started from the early stage of the device design and iterated through an early formative, completed with desk-based activities, late formative, completed with a focus group, and summative phase, that comprised a user test, and questionnaire filling. The identified usability issues are mitigated, the safety of the device user interface is confirmed and the training contents are defined and confirmed. Additional information regarding the user experience is collected and analyzed to identify further improvements of the device

Результаты мониторинга аэрозольной составляющей атмосферы в средних и высоких широтах и над акваторией Мирового океана

The article analyzes the observation data for the total optical thickness of the atmosphere at mid-latitude stations of the background air pollution monitoring on the territory of the Russian Federation for more than 40 years. The obtained results are compared with similar results in Northern and Southern Polar regions.The data of direct spectral observations of the aerosol optical thickness at the AERONET stations located in high and middle latitudes, as well as the spectral observational data over the Atlantic and Southern oceans collected during the voyages of research vessels to Antarctic and back, have been also drawn to the consideration. The analysis of observational data collected in such diverse conditions, allows evaluating the specificity and dynamics of aerosol pollution in various regions of the planet.В статье анализируются данные наблюдений за интегральной оптической толщиной атмосферы на среднеширотных станциях фонового мониторинга загрязнения атмосферы на территории Российской Федерации за более чем 40-летний период; данные спектральных фотометрических наблюдений за аэрозольной оптической толщиной на станциях международной сети AERONET, расположенных в высоких и средних широтах; данные спектральных фотометрических наблюдений в Атлантическом и Южном океанах, накопленные во время рейсов научно-экспедиционных судов в Антарктиду и обратно. Сопоставлены друг с другом результаты одних и тех же видов наблюдений в средних широтах и в северной и южной полярных областях. Анализ материалов наблюдений, полученных в таких разнообразных условиях, позволил оценить специфику и динамику изменений аэрозольного загрязнения в различных регионах планеты

Многолетняя изменчивость годовых сумм суммарной и поглощенной солнечной радиации в Арктике

Variability of total (Q) and absorbed (Q – R) radiation after the year 2000 at some Russian Arctic stations in comparison with the long-term variability of these characteristics since the beginning of observations and until 1992 was investigated. As estimating parameters, the normalized by multiyear averages for 1961–1990 of anomalies of annual sums of total and absorbed radiation were chosen. We have analyzed the variability of total cloudiness and integral optical thickness characterizing transparency of the atmosphere as the factors producing the largest influence on total radiation incoming to the land surface. The integral optical thickness of the atmosphere in the Arctic after 2000 was most likely determined by specifics of air pollutants coming to the Arctic atmosphere and was significantly higher in the western Arctic area, than in the eastern one. After 2000 practically at all stations considered, the income of total radiation appeared to be below the multiyear average. Significant by the absolute value, but different by the sign, changes of absorbed radiation were recorded. The long-term periods of decrease and the subsequent increase of the incoming solar radiation observed at the European stations and called as “global dimming and global brightening” were not revealed at the Russian Arctic actinometric stations.Исследована изменчивость суммарной (Q) и поглощенной (Q – R) радиации после 2000 г. по данным отдельных арктических станций в сравнении с многолетней изменчивостью этих характеристик с начала наблюдений и по 1992 г. В качестве оценочных параметров выбраны нормированные на многолетние средние за 1961–1990 гг. значения аномалий годовых сумм суммарной и поглощенной радиации. Проанализирована изменчивость общей облачности и интегральной оптической толщины, характеризующей прозрачность атмосферы, как факторов, оказывающих наибольшее влияние на поступление суммарной радиации. Интегральная оптическая толщина атмосферы в Арктике после 2000 г., скорее всего, определялась спецификой поступления загрязняющих веществ в арктическую атмосферу и существенно выше в западном арктическом районе, нежели в восточном. После 2000 г. практически на всех рассматриваемых станциях приход суммарной радиации оказался ниже многолетней нормы. Зафиксированы значительные по абсолютной величине, но неодинаковые по знаку изменения поглощенной радиации. Длительных периодов уменьшения и последующего увеличения приходящей солнечной радиации, наблюдавшихся на европейских станциях и названных глобальным помутнением и просветлением атмосферы (“global dimming and global brightening”), на российских арктических актинометрических станциях не обнаружено

База данных часовых и суточных сумм суммарной радиации на российских антарктических станциях: анализ изменения суммарной радиации за весь период наблюдений в Антарктиде

Given the significant changes in the climate on the planet as a whole, databases and archives of data on the main climate-forming characteristics of the atmosphere, collected over long periods of time in various regions of the globe and, in particular, in the polar regions, acquire a special role. Total solar radiation is one of the most important parameters affecting the energy balance of the Earth-atmosphere system. We have created a database (DB) of hourly and daily sums of total radiation (Q) at the Russian Antarctic stations, designed to study the radiation regime of the Antarctic, from the beginning of actinometric observations to 2019. The information presented in the database was collected at five Antarctic stations — Bellingshausen, Vostok Mirny, Novolazarevskaya and Progress. The database has undergone a state registration procedure and is registered under No. 2020621401. The article gives a description of the structure of the DB and presents detailed information for each station. To provide an example of how database information can be used, characteristics of the total radiation in different parts of the Antarctic continent are obtained. Thus, it is found that the average monthly amounts of Q in the continental part of Antarctica on the high plateau (Vostok station) in conditions of minimal cloudiness and high transparency during the Antarctic summer are maximum and average 1240 MJ/m2. At the same time, at the tip of the Antarctic Peninsula (Bellingshausen station) during the same period, the average monthly amounts of Q due to the almost constantly present cloud cover do not exceed 570 MJ/m2. In the coastal areas at the three remaining stations, the average monthly amounts of total radiation range from 908 MJ/m2 (Progress) to 950 MJ/m2 (Mirny). Estimates of variability characteristics of daily, monthly, and annual sums of total radiation at all the five stations for the entire observation period up to 2019 were also obtained. The absence of statistically significant long-term trends in the annual and monthly sums of total radiation at all the stations under consideration was noted. The results of their analysis indicate that there are no significant changes in the inflow of total solar radiation to the Antarctic surface over more than sixty years of actinometric observations.С учетом ощутимых изменений климата на планете в целом, особую роль приобретают базы и архивы данных основных климатообразующих характеристик атмосферы, собранных за длительные периоды времени в различных районах земного шара и, в частности, в полярных областях. Суммарная солнечная радиация входит в число важнейших параметров, влияющих на энергетический баланс системы Земля — атмосфера. В статье приведено описание созданной базы данных (БД) часовых и суточных сумм суммарной радиации на российских станциях Антарктиды. БД предназначена для исследования радиационного режима Антарктики с начала актинометрических наблюдений и до настоящего времени. База данных прошла процедуру государственной регистрации и зарегистрирована под № 2020621401. На основе содержащейся в ней информации были получены оценки характеристик изменчивости суточных, месячных и годовых сумм суммарной радиации на станциях Беллинсгаузен, Восток, Мирный, Новолазаревская и Прогресс за весь период наблюдений по 2019 г. Результаты их анализа свидетельствуют об отсутствии существенных изменений в поступлении суммарной солнечной радиации на антарктическую поверхность за более чем шестидесятилетний период актинометрических наблюдений

Adenosine thiamine triphosphate and adenosine thiamine triphosphate hydrolase activity in animal tissues

Adenosine thiamine triphosphate (AThTP), a vitamin B1 containing nucleotide with unknown biochemi­cal role, was found previously to be present in various biological objects including bacteria, yeast, some human, rat and mouse tissues, as well as plant roots. In this study we quantify AThTP in mouse, rat, bovine and chicks. We also show that in animal tissues the hydrolysis of AThTP is catalyzed by a membrane-bound enzyme seemingly of microsomal origin as established for rat liver, which exhibits an alkaline pH optimum of 8.0-8.5 and requires no Mg2+ ions for activity. In liver homogenates, AThTP hydrolase obeys Michaelis-Menten kinetics with apparent Km values of 84.4 ± 9.4 and 54.6 ± 13.1 µМ as estimated from the Hanes plots for rat and chicken enzymes, respectively. The hydrolysis of AThTP has been found to occur in all samples examined from rat, chicken and bovine tissues, with liver and kidney being­ the most abundant in enzyme activity. In rat liver, the activity of AThTP hydrolase depends on the age of animals

Passive sampling and benchmarking to rank HOC levels in the aquatic environment

The identification and prioritisation of water bodies presenting elevated levels of anthropogenic chemicals is a key aspect of environmental monitoring programmes. Albeit this is challenging owing to geographical scales, choice of indicator aquatic species used for chemical monitoring, and inherent need for an understanding of contaminant fate and distribution in the environment. Here, we propose an innovative methodology for identifying and ranking water bodies according to their levels of hydrophobic organic contaminants (HOCs) in water. This is based on a unique passive sampling dataset acquired over a 10-year period with silicone rubber exposures in surface water bodies across Europe. We show with these data that, far from point sources of contamination, levels of hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) in water approach equilibrium with atmospheric concentrations near the air/water surface. This results in a relatively constant ratio of their concentrations in the water phase. This, in turn, allows us to (i) identify sites of contamination with either of the two chemicals when the HCB/PeCB ratio deviates from theory and (ii) define benchmark levels of other HOCs in surface water against those of HCB and/or PeCB. For two polychlorinated biphenyls (congener 28 and 52) used as model chemicals, differences in contamination levels between the more contaminated and pristine sites are wider than differences in HCB and PeCB concentrations endorsing the benchmarking procedure